As I understand it, and someone please correct me if I'm wrong, within the ATPL exams an aircraft performance paper must be taken. This is either A, B or C. Performance A regards to that of an A320/B737 and is needed (I think) for employement on large jets.
(Perf C may be in PPL theory, but I'm not sure on that one)
Hope thats of some help, Gaz1